Human MD2 deficiency-an inborn error of immunity with pleiotropic features

Update on inborn errors of immunity

Ever since the first description of an inherited immunodeficiency in 1952 in a boy with gammaglobulin deficiency, new insights have progressed rapidly in disorders that are now referred to as inborn errors of immunity. In a field where fundamental molecular biology, genetics, immune signaling, and clinical care are tightly intertwined, 2022-24 saw a multitude of advances. Here we report a selection of research updates with a main focus on (1) diagnosis and screening, (2) new genetic defects, (3) susceptibility to severe coronavirus disease 2019 infection and impact of vaccination, and (4) treatment. Importantly, new pathogenic insights more rapidly affect treatment outcomes, either through an earlier and more precise diagnosis or through implementation of novel, personalized treatment. The field is growing rapidly, so awareness, communication, and collaboration are key to improving treatment outcomes.

Extracellular peroxiredoxin 6 released from alveolar epithelial cells as a DAMP drives macrophage activation and inflammatory exacerbation in acute lung injury

Acute respiratory distress syndrome (ARDS) is featured with acute lung inflammatory injury. Our prospective study found that higher levels of peroxiredoxin 6(PRDX6) were detected in bronchoalveolar lavage (BAL) fluid from ARDS patients. Elevated PRDX6 was also correlated with monocytic activation and poor prognosis in ARDS patients. To investigate the origin of extracellular PRDX6, we conducted in vitro and in vivo experiments, demonstrating that PRDX6 can be actively released from alveolar epithelial cells under stress conditions. Our study demonstrated that it could be released from injured lung epithelial cells into the bronchoalveolar interstitial space in mice with acute lung injury and in vitro experiments. Moreover, exogenous PRDX6 was shown to activate the TLR4/NF-κB signalling pathway and induce M1 polarization of macrophages. Notably, the inflammatory effects of PRDX6 were mitigated by specific inhibition of the TLR4 (Toll-like receptor 4)-MD2 (Myeloid differentiation factor 2) complex. Using molecular docking simulations and in vitro binding assays, we confirmed a direct interaction between PRDX6 and MD2, further supporting its role as a damage-associated molecular patterns (DAMP) in ARDS. Our findings suggest that extracellular PRDX6 in bronchoalveolar lavage fluid could be a new DAMP factor in ALI, providing new insights into the pathogenesis of secondary hit in ALI/ARDS and highlighting PRDX6 as a potential therapeutic target for mitigating lung inflammation.

Peptide TaY Attenuates Inflammatory Responses by Interacting with Myeloid Differentiation 2 and Inhibiting NF-κB Signaling Pathway

A balanced inflammatory response is crucial for the organism to defend against external infections, however, an exaggerated response may lead to detrimental effects, including tissue damage and even the onset of disease. Therefore, anti-inflammatory drugs are essential for the rational control of inflammation. In this study, we found that a previously screened peptide TaY (KEKKEVVEYGPSSYGYG) was able to inhibit the LPS-induced RAW264.7 inflammatory response by decreasing a series of proinflammatory cytokines, such as TNF-α, IL-6, and nitric oxide (NO). To elucidate the underlying mechanism, we conducted further investigations. Western blot analysis showed that TaY reduced the phosphorylation of key proteins (IKK-α/β, IκB-α,NF-κB (P65)) in the TLR4-NF-κB signaling pathway and inhibited the inflammatory response. Furthermore, molecular docking and molecular dynamic simulations suggested that TaY binds to the hydrophobic pocket of MD2 through hydrogen bonding and hydrophobic interactions, potentially competing with LPS for MD2 binding. Collectively, TaY is a promising candidate for the development of novel therapeutic strategies against inflammatory disorders.

Lymphocyte antigen 96: A new potential biomarker and immune target in Parkinson's disease

BACKGROUND

Lymphocyte antigen 96 (LY96) plays an important role in innate immunity and has been reported to be associated with various neurological diseases. However, its role in Parkinson's disease (PD) remains unclear.

METHODS

Transcriptome data from a total of 49 patients with PD and 34 healthy controls were downloaded from the Gene Expression Omnibus (GEO) database to analyse the expression pattern of LY96 and its relationship with gene function and immune-related markers. In addition, peripheral blood samples were collected from clinical patients to validate LY96 mRNA expression levels. Finally, an in vitro cell model of PD based on highly differentiated SH-SY5Y cells was constructed, with small interfering RNA-silenced LY96 expression, and LY96 mRNA level, cell viability, flow cytometry, and mitochondrial membrane potential assays were performed.

RESULTS

The results of the analyses of the GEO database and clinical samples revealed significantly abnormally high LY96 expression in patients with PD compared with healthy controls. The results of cell experiments showed that inhibiting LY96 expression alleviated adverse cellular effects by increasing cell viability, reducing apoptosis, and reducing oxidative stress. Gene set enrichment analysis showed that LY96 was positively correlated with T1 helper cells, T2 helper cells, neutrophils, natural killer T cells, myeloid-derived suppressor cells, macrophages, and activated CD4 cells, and may participate in PD through natural killer cell-mediated cytotoxicity pathways and extracellular matrix receptor interaction pathways.

CONCLUSION

These findings suggested that LY96 might be a novel potential biomarker for PD, and offer insights into its immunoregulatory role.

High-throughput omics technologies in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic, relapsing intestinal disease. Elucidation of the pathogenic mechanisms of IBD requires high-throughput technologies (HTTs) to effectively obtain and analyze large amounts of data. Recently, HTTs have been widely used in IBD, including genomics, transcriptomics, proteomics, microbiomics, metabolomics and single-cell sequencing. When combined with endoscopy, the application of these technologies can provide an in-depth understanding on the alterations of intestinal microbe diversity and abundance, the abnormalities of signaling pathway-mediated immune responses and functionality, and the evaluation of therapeutic effects, improving the accuracy of early diagnosis and treatment of IBD. This review comprehensively summarizes the development and advancement of HTTs, and also highlights the challenges and future directions of these technologies in IBD research. Although HTTs have made striking breakthrough in IBD, more standardized methods and large-scale dataset processing are still needed to achieve the goal of personalized medicine.